High-voltage circuit breaker



Aug. 4, 1953 J. D. WOOD ET AL HIGH-VOLTAGE CIRCUIT BREAKER OriginalFiled Jan. 11, 1947 3 Sheets-Sheet 2 Attorneys 1953 J. D. WOOD ET ALHIGH-VOLTAGE CIRCUIT BREAKER 3 Sheets-Sheet 3 Original Filed Jan. 11,1947 ULILJHUHLIHUIUUUUHUUUWLJHH S M Q m n NIOWP E03 0 W dH W CA D h ws.. m OP 5 A Patented Aug. 4, 195 3 urea-veer Joseph-D. llarby, Cas

well,,Philadelphia, Pa., assignors to I. T. E.

Circuit Breaker Company, v Pliiladelphia, Pa}, 3'

cbrporatiofiof Pennsylvaniai I I I J Original applicationflanuary. 11-," .1947",. Serial :No'. 721,648,;npw ratentNo. 2,613,299, dated Ct -iher 7, 1952. Divided and this application June 4, 1947, Serial N 0.752,427

Ourfpresent invention which advisionfof our application Serial No.721,648, filedJanuary 11, 1947, now PatentNo. 2,613,209, datedoctober 7,1952, relates to high voltage; high capacity; circuit'breakers, and moreparticularly to circuit breakers having an interrupting rating oi 50,000kvaand better in anyvoltage range between 2300 and 5000 volts and atcurrent ratings of 600and 1200 amperes. v

Essentially our'invention is directed to the productionof high voltagehigh capacityair break switchgear in such a manner as to provide" theincreased interruptingcapacity required by means of the simplestelements which are manu factured and assembled by mass v productionmethods in the most economical way. a i

This novel circuit breaker includes a simple unitary arc chute structuremade as a single unit provided with a disconnect and so arrangedthat' itmay readily be mounted on the circuit breaker and connected thereto orremoved-therefrom as a whole without the necessity'for'special tools.

Ournovel arc chute thus combines the essential ideas of simplifiedconstruction ior'greater economy and simplified arrangement in theformbf a single unit assembly which may readily be mounted on any circuitbreaker ofthe class to which the'arc chute is to be applied. The arechute may readily be removed for inspection' of the contacts of thecircuit breaker or for replacement or repair of anypart that may re-"quire such replacement or repair.

In a high voltage high capacity. circuit breaker," one of "themost'important problems is the provision of proper insulation and theavoida'nce of any dielectric breakdown which may: occurinthe operationof the circuit breaker.

An important object ofour inventionythere fore, is the novel arrangementof thenarc chute so that the front are runner or arcing thorn isentirely disconnected from the back terminal in 5 any position of thecircuit breaker; whether closed or open. This is achieved by soarranging the movable arcing contact that it may transfer the arc to thefront are runner solely: byireas'onz" of its proximity thereto during aportionrcfthe opening movement; the arcing contact at the completion ofthe openings movement-moves suf ficently far away from the frontarcqrunner'so' that 'there'is no connection or likelihood ofanyconnection therebetween; ",This'front ,arcrrunner is entirelydisconnectedand .thewfrontlofithe arc-1' t member "is completely safeforhandlin'g even while the circuit breaker is racked into posi tiQH-Tplates on 'each side Thefblow out mechanism comprises essentiallya"U-'shaped ironstructure, the base of which is V surroundedhy'theblow-out coil and the legs of which extend out perpendicularly to thepanel on which the-circuit breaker is mo of the- -U-'shaped ironstructure carry the arc chute';'-and the arc'chute may he slid on to orI off these 'legs for placement or removal.

' The'blo'w-out iron circuit is made up of a core around which theblow-cu ends-of the co're are attached the side plates which projectforward nearly the entire depth of the arc chute. or' 'runners andsupports for the arc chute and the complete assembly is thus supporteddirectly on the back panel support.

Her'eto'iorein the construction of blow-out mechanisms, it has beenfound that a concentration'of flux at the coil end occurs with solidside plates 'so'that only thecoil end of the arc chute is used;

Accordingly,another object of this invention is the novel arrangement ofthe blow-out iron in such a mannerthat the flux is relatively evenlydistributed overall of the side plate area so that the-entire arc chuteis used.

In actual operation we ha y H g I, ve found'that an economicalcombination of f our 4/ inch thick 7 gave a fairl tribution over thefull length.

In addition, and in out effect, auxiliary b tach'ed to the runnerchu't'e'and 'divert part ofthe main down into the vicinity of the contaBythis novel construction the b ture'and the arc chute'structure aremechanically separated and independent of each other so that the-arcchute is much lighter and easier to remove low-out iron 'plates areatfor inspection and so thatthe blow-out construe tion acts as a supportAccordingly an ob construction of a high capacity highvoltage"cir le ofinterrupting arcs "of y 01' even-better, andeconomical m design andconstruction, capable of unitisub' assembly manufacturing operation} andsoreducedin cost that its price may compare "favorably and" at timeseven be lower '7 for the arc chute.

50,000JkV a. lcapait unted. These legs t coil is wound; to theTheseplates also act as slides y even flux dis order to enhance theblow-' strip on each side of the arc,

low-out strucject of ourinvention is the I than that of many lowercapacity lower voltage circuit breakers on the market today.

In actual practice, the commercial circuit breaker hereinafterdescribed, which was designed for 50,000 kva. interrupting capacity hasbeen subjected to four successive tests at 63,000 kva. interruptingcapacity although standard practice requires only two successive testsat the full rate interrupting capacity. I

Furthermore, by changing the material of the arc chute plates it wasdiscovered that the interrupting capacity of the breaker was greatlyincreased. For instance, in one case, a breaker that would interrupt 65mva. was found capable of interrupting current in excess of 125 mva. byno other change except the change in the material of the arc chuteparts.

It is therefore an object of this invention to provide superiormaterials for arc chute parts.

In addition, in high capacity circuit breakers which are designed tointerrupt arcs of substantial kva., it frequently occurs that theblow-out mechanism will effectively move the arc into the arc chutecausing it to be extinguished at or near the full rated interruptingcapacity, while the blow-out mechanism is not able to perform the job ofmoving the arc up into the arc chute at very low current valuesrepresented by the charging currents of transformers or cables owing tothe fact that the flux through the blow-out mechanism or coils is verylow and ineffective. This has resulted, in some prior art circuitbreaker construction, in the addition of further devices such as puifersand the like to assist the blow-out coil in performing its operation.Alternatively the prior art blow-out coil has been provided withsufficient turns to obtain the required ampere turns even for lowcurrent failures. Such prior art devices have thus utilized theexpedient simply of assisting an inefiective construction by addingadditional construction thereto rendering it unnecessarily bulky.

Another and primary object of our invention is the arrangement andconstruction of the blowout mechanism of our novel circuit breaker sothat it may move an are at low interrupting current as well as an arc athigh interrupting current properly into the arc chute so that the samemay be extinguished; the said blow-out mechanism operating for thispurpose over the entire range of interrupting capacity of the circuitbreaker without the necessity for additional aid or other expedients.This we achieve in part by passing only a portion of the arcing currentthrough the blow out coils, the percentage of such current decreasing asthe fault current increases. For very low value currents, we provide aseparate arc chute.

The foregoing and many other objects of our invention will becomeapparent from the following description of the drawings in which:

Figure 1 is a side view in perspective, partly broken away showing ournovel circuit breaker assembled and mounted on a truck.

Figure 2 is an enlarged side front view in perspective partially brokenaway showing the lower terminal assembly, upper terminal assembly, theblow-out coil assembly and the movable contact bridge assembly.

Figure 3 is a side view of the arc chute assembly.

Figure 4 is a front view of the arc chute assembly.

Figure 5 is a top view of the arc chute assembly.

Referring now to Figure 1, our novel circuit breaker is shown preferablymounted on a movable truck. The movable truck comprises a back mainsupporting structure which includes the vertical support members l0 andII connected together and interbraced at the lower end by the Masonitepanel I2 and at the central and upper portion by the cross-bars l3, l4and 15 which are connected as shown, in any appropriate manner, as forinstance by bolts and nuts to the vertical members I0 and II. The lowerends of the vertical members [0 and H are provided with bearings H and18 for the shaft l9 which carries the rear wheels 20 and 2| of thetruck. The vertical members It! and H together with the cross bracingelements above described and the wheels 20 and 2| constitute a singleunitary member of assembly.

Certain of the assemblies are standard and require no specificdiscussion here. Thus, the control panel assembly 4'! and the trip unitassembly 48 may be substantially standard units which require nospecific description. Also, the control switch contacts indicatedgenerally at H: of Figure l and the grounding contacts II, 12 of Figures1 and 2 may be standard units. The essential elements as above pointedout with respect to these units is the unit assembly arrangement whichis possible with the construction herein shown.

The rear end of the operating mechanism assembly 46 is supported on thecross bar 14 which is held by the bolts 15, I5 across the top of thelower panel :2. Cross bar 14 also provides means for supportingadditional assemblies. The specific novel assemblies or sub-assembliesshown in Figure l and forming an essential part of the novel circuitbreaker here shown are the lower terminal asesmbly shown in Figure 2,the upper terminal assembly of Figure 2, the movable contract arm orbridge assembly of Figure 3, the blow out assembly of Figure 2, the arcchute assembly of Figures 3, 4 and 5. The specific operation of theseindividual assemblies renders possible the entire high speed highcapacity circuit breaker which our novel unit embodies.

The various assemblies above mentioned will be described in order, goingfrom the bottom to-v ward the top of the circuit breaker without:specific emphasis on any one of the assemblies. over the other.

It must be emphasized, however, that an im portant feature of thecircuit breaker is in thenovel are chute construction in conjunctionwith the novel blow out construction.

The operating mechanism utilizes as closely as possible the simpleprinciple of the lever op-. erated switch with only enough additionthereto. to provide automatic response to over-current; conditions inorder to trip the circuit breaker and also to provide a solenoid closingmeans. The. simplification of this operating mechanism makes possiblethe production of the inexpensive circuit breaker herein described.

Thus, while the arc chute assembly and the blow-out assembly makepossible the high capacity operation and high speed operation which areesesntial to the operation of the circuit breaker as a whole, thesimplicity of the other assemblies makes possible the economical andefficient construction.

The individual unit assemblies facilitate storage of parts preparatoryto final assembly and thus make it possible to fill orders quickly.

Thus. the first sub-assembly which consists of the back panel and theback wheels 20 and 2| is essentially a simple flat member which mayreadily be stored anddoes nctitake' up any-tutstan'tial amount or space'(see Figure 1').

Heretofore, the diffi'culty encountered injpremanufacture ofsub-assemblies 'injanticipation of future orders resided in thefact thatthe mainframe of the circuit breaker or o'therjjswitch gear usually wasas big'as the circuit breaker itself, so that the manufacture and"especially the storage of the main 'frame presented [the same problemas the storing of an entire circuit breaker. No real economy waseffected by' -pr'emanufacture of the main framesince'the entire circuitbreaker could be stored just as readily.

By means of our novel device, the back ,panel and the rear wheels of thetruck whihconstitute a single flat structure may readily be storedawaiting specific orders for assembly of Specific circuit breakers.

The truck structure'is' completed byimeans of a lower or bottom platform23 which carries a front wheel 24 in the front swivelglti (Figure 1).The'bottom platform 23's secured at the rear end of the lower end of thevertical members l and l I above the bearings l'l and l' fl 'for therear wheel. The bottom platform 23in connection with the back panel formthe vertical supporting members I0 and l I and their interbracingstructure and taken together withthe rear wheels 20 and 2! and the frontswivel wheel 24 comprises the truck or mounting for the circuit breaker.Thus the bottom platform 23 and the front swivel wheel constitutes asingle sub-assembly which may readily be stored without requiring anyadditional space and which may readily be attachedbytwo screws to thelower end of the vertical members I0 and H. I This type of unitarysub-assembly construction which may readily be interconnected with otherelement in order to make a. complete truck, facilitates modification andvariation of sub-assemblies in order to meet the specific orders.

Thus in the event various control elements must be multiplied to asubstantial-extent in the final circuit breaker thus requiring perhaps acustom built lower platform 2 3, ;19hi8510W61 platform 23 may bebuilt-tmthe unique speci fications of the customer-and may thenbecombined with the standard back panehconstruction which is kept instock. However the entire truck construction including the-first andsecond Sub-assemblies v des r -bedar bu' ltiin fu l anticipation of allrequirements to which the particular 1 circuit breaker may; ba -put, .sothat particular custom madeback or bottomgportions of atruck will berequired only insexceptional cases. "The upper terminal assembly;;30,;and the lower terminal assembly 3! for. each of the three poles isformedfrom a single bar of copper of rectangular cross sectionappropriatelyinsulated by phenolic insulationas-describedmoregspecifically hereinafter in connection with-Figure 2.'Each of the vertical members. l 0, ltand t'z is'rece'ssed at 33, "33 toreceive the terminal members and accurately position the same. a v

Each of the vertical reinforcements" |0 ll and 32 is'a rectangular steelmember so that while the recesses33f33 are cut out in the verticalreinforcement they are inc'i sed only in the o tion of the rectangular;steel. member which is normal to the back panel- 56. Thelegsofreachof"the"rectangularmembers l 0, j l and 3 2 carry thebolts d6, 36 which"engage-thefiangemembers 35-ofthe terminal element Esta tr the upper andlower terminal as- 13, which is'secined v H and 32 by the'bolt guide thetruck into and.

snitlvmeiiiliers '3'0 r a d 531i tea-waste spas;

biased disconnect "contact "elements at, -at "also hereinafter morespecifically described in con-- nection with Figure 1, but. shownalsoin'Pa'tent Numberg2,'029;02'8. 'Ihe'i nterm'ediate "cross "bar to't evertical members 'HI,

WU, also carries at its outer end thewheels 42 ,on anappropriate shafteitensio'n 'the'reonthe said wheels 42 cooperating n th .0mma rwn out of'the'.:compartment witnappropriate tracks properly; J I .Thje rackingandindic'ator assembly shown enerally Lat 43 "of Figure 1 also *carries{the front wheels 344,, 1414 j to ride on 'Tthe guide tracks .of thecfompartineritiih .Whi'chithe. circuit breaker is "housed.

course has as many. poles as there are .upper and lower terminalassemblies,,.three in the particular instance shown, is p'rovided withcontact elements hereinafter more particularly described in connectionwith Figure 2. I'hei-blow out coil assembly 53 which includes. the ,coilf5f4 ofIFigure '2 and the laminated blow outiron-legsii55,

mounted on the upper insulating vbackpanel- 56 also across the bars I15and 7 l4 .and the "upper portion of vertical supporting members 10 =.and

Hand issupportedthereby, I

-Itis spaced. from. the. bars [0, ll, 32,, J4, and

15 by'the upper insulating back panel f55 which panel is securedacrossthe bars Mi, Ll I and -32 asshown in Figure 2, Appropriate openings: 59,Marc provided in-the panel 56 to permit; the terminal members 30 and 3|to project there through: in amanner shown in Figures i and 2.. The arcchute assembl 51 is-supported-.by' the blow out assembly 53 andparticularly .by the laminated legs 55 of the blowout ironwhich ridebetween the bracing bars 58, 58 on each side of the-arc chute as showninFigures 1v and 3, and as will be, more specifically describedhereinafter in connection with Figures 1, 2 and 3. The are chute isentirelywsupported by the laminated legs 55 of the blow out iron on eachside, being retained in position by the "latch assembly 6| (Figure 3)also'hereinafter more specifically described. a

All of the elements of the circuit breaker as will beseen from aninspectiontof Figurel, and of subsequent figures may beinexpensivelyma'de from ordinary sheet metal or cut from ordinary bars,and 1 no complicated casting or machining operation is required, thusleading to great economy in the manufacture and n assembly .of thedevice. s p

Also from the previous discussion it will i be seen that the assemblyvoperation consists ofta number of units as above described, each ofwhich may readily be. stocked and kept. in storagenwithout consuming an.undue amount ofsspacedand which may readilylbe assembled simply'lby afew bolt or". screw manipulating operations tointerconnect an entirecircuit breakerifromthe .unit assemblies.

Lowcrter'mz'nal dsseiiit'zy' The 'idwertetmmai assen'itit is. shbwifisFigures 1 and 2 comprises a bar of copper I50 insulated by an oblongBakelite tube II with a conductive inner lining into which it has beenpressed. The front end I52 supports the movable contact bridge assembly50 in a manner hereinafter specifically described, while the maindisconnect contacts 38 are secured to the rear end The lower terminal 3Ihas the side flanges I56, I56 secured thereto in any suitable manner, tocooperate with the movable contact arm as shown in Figure 2. In theusual procedure for insulating a terminal bar such as that shown inFigures 1 and 2 phenolic insulation material is wrapped around the barand tightly pressed thereon. This is a complicated process which must beperformed on special machinery and by those having special skills in thefield.

In the present construction, instead of wrapping phenolic insulationtightly around the bar I50, the flat tube I5! is used, said tube beingprovided with a conductive lining I62. This tube is placed over the barI50 and then pressed into tight engagement with the bar I50 to providethe insulation cover therefor.

The principal reason for wrapping the insulation in the prior art wasthat no minute air pockets could be permitted since at high voltagesthese would result in Corona discharge, causing progressive dielectricresulting in breakdown of the insulation. Consequently great care wasrequired in the wrapping of the insulation.

We have discovered that by using a sleeve of insulating material andmaking the inner surface of the sleeve conductive, the sleeve may simplybe pressed down around the tube to conform with the contour of the barand provide a completely engaging surface to surface contact thusaccording any deleterious effects resulting from any minute air pocketsthat may remain. Thus where the prior cost of wrapping such bars was inthe neighborhood of $12.00 per bar and it was necessary to send the barout to be wrapped by special machinery, our invention makes possible theinsulation of the bar at the circuit breaker plant at a cost of about$1.50.

Upper terminal assembly The upper terminal assembly 30 shown in Figures1 and 2 also comprises a bar I60 of copper having an insulating sleeveI6I mounted thereover in the same manner as previously described inconnection with the lower terminal assembly of Figure 4.

The rear end of the bar I60 has the conformation I54. to receive and.hold the main disconnect contacts 38 shown in Figures 1 and 2. The frontend of bar I60 has secured thereto the stationary main contact I61 andthe stationary arcing contact I06 (Figure 3). The upper end of the frontportion of bar I60 has secured thereto the insulating plate I having theupper slotted extension I10a. Connector I1I is secured in any suitablemanner to the insulating blocks I65 and I68 but isinsulated from thecontact bar I60 and the arcing contact I66 and stationary contact I61.

Connector I1I has a cut-away portion at its front end between which, andspaced from either edge, the forward end 208 of the movable contact arm1, comes to rest when the contacts are in engagement as will bedescribed hereafter.

M mqcble contact assembly In Figure 2 we have shown one of the contactdeterioration and thereby arms 80. The contact arm comprises a pair ofcopper bars I80, I8I between which is secured, at the upper end by pin205, the arcing contact arm 204. The movable arcing contact arm 204 isheld in proper spaced relation by the spacer washers I84--I84, all ofwhich are forced into proper current carrying relation by the springwashers 233-233. The upper inside edge of the copper bars I80I8I carryspecial arc resisting silver alloy contact blocks I85 which comprise themain movable contacts.

The lowerends of the bars I80 and I8I is provided with the registeringopenings to receive the pin I81 (Figures 1 and 2) which pin passesthrough the openings.

The pin I81 is provided on each side with a lug I (Figures 1 and 2)carrying the bar I9I which passes through opening I93a (Figure 2) of theside flanges I56. Compression springs I93 on each side are capturedbetween flanges I56 on each side and the lug I90 of pin I81 on each sidethus forcing the lower end or pivot of the contact arm out toward theright with respect to Figures 1 and 2 at the pivot point I86.

The contact arm eifectively pivots about pin 200 (Figure 1) which isconnected between the arms I8I and I80 and which carries the end of link5I connected to contact operating arm 52. Thus, compression springs I93force the contact arm 80 to rotate counterclockwise about the pin 200within the limit of the length of slot I88 on the lower terminal andthus forces the movable contact I85 into close wiping engagement withthe stationary contact member I61 (Figures 1 and 2).

In any position of the arm 80 other than the closed position of the arm80, compression springs I93 push the pin I86 over to the far right endslot I88 of the lower terminal of Figure 2. When the contact arm reachesthe closed position of the contacts, the movable contact I85 bearsagainst the stationary contact I61 and as the link 5| forces pin 200 andcontact arm 80 into the closed position, the spring I93 yields becauseof the slope of the angular slot I88 to permit the wiping action tooccur between the contacts I85 and I61 and the contacts to close firmly.

The forward end I52 of the lower terminal is provided with silver alloyinserts 202, 202 to bear against the inner surfaces of arms I80, I8I ofcontact arm 80. Thus it will be seen that no pigtails are use, butappropriate elements are used on pin I81 to squeeze the lower ends ofarms I8I, I80 against the insert contacts 202 on the lower terminal.

The contact springs I93 are located close to the pivoted stud I81 whichis a distinct advantage because they are well away from arcing zone. Theconnection of link 5I to the contact arms is at a point 200, as abovepointed out, well above the center point of the arms 80, so as to makethese contacts blow-on contacts as explained in the followingdescription.

In ponse to a rise in currents, magnetic forces developed in thesecontacts tend to increase contact pressure at all contact points. Thearcing contact arm 204 is pivotally mounted on the pin 205 between thecontact arms I80, I8I and the spacer washers I84, and is provided withan arcing contact element 206 and the horn 201. The lower end of arcingcontact arm 204 is connected by the floating pin 2") to the link 2 IIwhich in turn at this lower end bears against the milled surface 2 I2 ofthe milled pin 2 I3 carried between the arms I80, I8 I.

Tension spring 2 I5 connected between lug 2I6 andspring eye 2 l 1 is:arrangedrto rotate link .21 I clockwise around the bearing furnished byth mil-led-portionliz. of pin. 213.- Thelug. 216; is adjustably mountedon screw 220 which in turn is received in the tapped openingt22l of.pin. 222 carriedjetween-the-arms [80,181. Rotationtof screw220 resultsinmoving lug. 216; to change the tension of spring 215- and thus:increase.v the bias thereof;

Spring 2l5 thus acts on-links- 2| I; tocause the toggle 241-210-404 tocollapse. in a direction to force the arcing contact 206 to the left.The full collapse of this toggle is prevented: by the adjustment ofscrew HO-which bears againsttthe end 225' of arcing contact arm 204.Tension spring 2l5, however, thus drives the arcing con.- tact element206 out to the left with respect to Figure 3 where it will make contact.with the stationary arcing contact I66 before. the main contacts engageand where it will maintain contact with the stationary arcing contactuntil after the main contacts have separated.

Since the center 205 of arcing contact arm 204 is well above themid-point thereof, a blow-on action of the arcing contact occurs, alsothus 7 ensuring that the arcing contacts will remain firmly inengagement until the main contacts have separated;

The position of the arcing tips 206 above the main contacts I61 forms anupward loop in the circuit which tends to initiate a blow out action tostart the arc upward when drawn.

In order to protect the lower terminal structure against any possibledefect in the arc chute or blow out mechanism which would tend to drivean are down, an insulating shield 230 is provided secured to the screwsI83 and flared out to protect the uninsulated portion of the lowerterminal bar I50.

Spring 2l5 ensures that the movable arcing contact will move intoengagement with the stationary arcing contact as the contact arm beginsto open and before the main contact separates. The arcing contacts willthen stay in en- :gagement for a substantial portion of the openingmovement depending on the settingof screw 220 (Figure 2).

Blow out assembly -'I'he blow out assembly 53 comprising thetcoil 5'4and the laminated blow out iron Elegs 1555a].- r'ea dy referred 'to inFigures 1 and :2, is shown *more specifically in Figure 12. The coil 54is connetted by the lead 235 and bolt 12 36 'CFigures ,1 and 2) tot'h'eupperterminal-bar 1| so. The .opposite end of coil 54 is connectedby :lead .238 to ext 'nsifo'n 11m on contact bar -|"H :passing lthrougha lot in the upper 'exten'sion :.I 7.022 :of insulating 'st'rip l -HI(Figure3'). Coil:54 is woundaon-anriron core 240 to which is secured thelaminated blow out iro'n leg's 5'5 on either si'de.

, We havefound that preferably rour such:side pistes on each side ithickensures ;a :proper -distiibiition of magnetic blow :out flux 'over thefull length of the -side 'Splates. .-Also we have found that in order toobtain a proper blowout "without inserting to :much; impedance 1: in

is with" the ar'c, itiis desirable rthatrthe coil 4jc'on'sist of 18':turns 'ofs copper strips of; 5% x Ih'e side frame imembers 242, 242(Figure :2) of the blow-out assembly aresecured' against the cor e' 240by bolts 2-43 which: :also secure; the plates '55 against the core.:The" side iframe members 242 or the 'blow out assembly have securedtherelietween the upper block 245 bye-mean ot .pin

2.46.. and the... low r. l ck not sh wn) y means fl'p n 4 nd plat .49jjy. means. fl g ifli g Block 245 and ts. or pon in q r hlqs are providedwith ap ed p pinesjb me n f W ich. the entire lpwr t. as emb y me fbreadily securedto the frame ot thecircuit brealg er. It Willtthus beseen that the entire blow; out assembly, may b eadil moun ed on. nd rmov d. from. he ircui b eaker a pa e unit.

Arc chute;

The blow-out. assembly serves as support-for the arc chute described inEigures2, 3-, 4and 5 The are chute. assembly 51 mounted abovethe contactassembly 80 provides for a positiveand efiicient are interruption, Itconsists" of insula tion side walls 251, front and back: arcru em 29!and 290 respectively and a series of} ce ic plates mounted inspacedrelation transve e of the a c path; nd; strong ma n tic l w b field toforce the arc into the are chute.

The sides 2 51; (F gures 3- and 5). have fastened at ir lower r ion.adja nt t e ar e a a; i ner ar r s n i ti ice EW tZ-QQ at specialcomposition hereinafter described. arc resisting plates 269 arechanifered along their up r ed es a il-.262 to. p ov de a s rai htlocking edge for the cross plates 2-611 and the sp ce s. 26 h ow r en so the r ss plates 260 and the spacers 2 1 a e ap rop iat y s aped to fitthe chamfered edge 262.

As the arc is driven into the chute by the magnetic field, it; passesrapidly through the arse):- tineuishing ceramic la e 2 hi h are ec.-taneular in sh pe t ir op and ave a one tapered lower edg ext din from te cente of one side of the p a e to the low corn r on the opposite sideof the Pl te- A e ami spac 26| is provi ed t sup o t ea h p ate and nostion it with respect to adj ent pla s an fo m with the long taperedsuriac of he p ate. a tr angular opening with the apex at the top torthe passage of the arc. Each plate with its spacer presents a decreasingarea for the are a it rises and gradually squeezes it into a narrow 81913.01.

The platesrZBil are assembled alternately an interleaved relation andspaced tram ea h oth r so that the long tapered surfaces ,cross at thecent r or the chute directly above th Path .Q the are as it travels upthe chute. As the arc passes the cross over point of the plates, it isforced into a zig-zag or sinuous path gradually but'r pidly in re sin{it l n th nd brin in it into co ta t :with lar r and la e ri tfa es ofth pla shea mu t uebe za b undth edges of the plates which are.eifective in circuit interruption. The positive andgflicientarcinterruption is afiected by the cooling, length ng and squeezing of theare -at ;nun erouspoints all along its path.

-Provision for the interruption of .low ,current arcsiis built intothearc chute. Nomovin arts or auxiliary equipment are necessaryr Shortbir-,cuit or normal over {currents .are' extinguished before the-movingarchorn 20,1 p,asses the front are 1 runner. The -.arc formed by curr ent sI ,of .low value is extended in the chute} beyond the .front are runner218i and.eifectivelyconled and deionizedtbyla set of plates .322(Figure.-.4) .located in .thewcurrent path.

. ,Arc travel toward the. front, of the QDPP i -volves, ,a transfer fromI the arc tcpntact arm 20 1 to :the forward "are runner. The. absence ofthe re rn, con e n-from. t i rr nt e tt h s owe' lead is a new featurein high voltage breaker design. Without this connection, the dielectricstrength of the open breaker is not dependent upon the arc chute, whoseinner surfaces are bound to deteriorate through use. Without thisconnection, the are between the contact arm 204 and runner continues aslong as the arc exists. On high values of current, the arc isextinguished before the arc contact arm 204 passes the runner.

Progress of the are up into the chute brings it in contact with thecross plates 260 which are shaped and assembled so as to cause the arcto follow a gradually increasing zig-zag form, thereby securing a longarc length in a short length of chute. Maximum length in a crosswisedirection is realized at a point opposite with the top of the blowoutiron side plates 55 where it enters a narrow confining slot 301. Thelength of the plates 268 above this point is used to cool and deionizethe incandescent gases which result.

When the current to be interrupted is of low value, low magnetic actionexisting at that time is still sufficient. The are is extended by thelong travel of the arcing tips and cooled by the specially locatedplates 322 below the front areing horn 29!.

The plates 268 are held in position in the arc chute by the insulatingcross bar 263 (Figures 3-5) carried in the slot 264 of the end pieces261. Insulating cross bar 263 is securely fastened by bolts 265, 266respectively, at the front and back end pieces 261 of the arc chuteassembly 51 which extend up above the side plates 251.

The side plates 251 are connected together at the front and back end ofthe arc chute by bolts 268 which connect them to the front and backstrips 261. The side plates are provided with insulating bracing bars 58secured thereto by the bolts 268 and spaced apart by the width of thelaminated blow-out iron legs 55.

The materials used in the construction of the arc chute play anextremely important part in the performance of the circuit breaker.

The side plates 251 are made of Bakelite with a layer of fibre on eachside. During interruption not only full voltage is applied to theseplates, but frequently switching surges of very high value. areencountered. The high insulating value of Bakelite is desired but italone would not be satisfactory since it has the characteristic ofcarbonizing and tracking if any arc or high temperature are gases comein contact with it.-.

Consequently, the Bakelite is coated with fibre which does not have thischaracteristic. Furthermore, an arc-resisting insulating varnish isapplied to the fibre to keep it from absorbing moisture. Furthermore,the spacers 26l for the crossplates 260 completely line the inside ofthe arc chute in the lower part where the arc is drawn and prevents theare coming in contact with the side plates at any point.

The material of which the cross plates 260 and the spacers 26! are made,determines to a large extent the ability of the breaker to interruptcurrents. The least expensive material that is at all suiable for thisapplication is the asbestos cement board called Transite. This materialgives fair operation and for low interrupting capacities is quitesuitable. In an effort to increase the interrupting capacity, numerousmaterials were tried. Gas forming materials such as fibre were found tobe unsatisfactory as they increased the display incident to circuitinterruptions and the excess gas had a tendency to initiate arcing inother parts of the breaker.

Inert materials 7:} are on the were better. Porcelain, while quite goodwas too fragile and could not be manufactured in thin plates withsuflicient accuracy to make it practical.

By far the best material found was the glass bonded mica consisting ofmica dust and glass fused and pressed at high temperature and pressure.It is inert at the temperatures encountered in the arc chute, anexcellent insulator, does not absorb moisture and is a non-gas-formingmaterial. This material when used for the are plate and spacersincreased the interrupting capacity to more than twice the value shownby other materials. It is used not only for the cross plates 260 andspacers 26! but also for the arc resisting plates 269 that come incontact with the arc.

The arc chute may be mounted in position by being slid on to thelaminated blow-out iron legs so that the reinforcing bars 58, 58 act asrunners to receive the laminated legs 55 in the manner shown especiallyin Figure 1, thus holding the arc chute in position.

In order to ensure a further distribution of magnetic blow-out flux downinto the region of the contacts, an additional iron plate 210 (Figure 1)is provided on each side of the arc chute secured to the bracing bars 58by screws 21l and having extension 212 extending down into the re ion ofthe contacts outside the plates 51.

The blow-out flux through the laminated blow-out iron legs 55 is alsocommunicated to plate 210 and by extension 212 is communicated down intothe region of the contacts to increase the blow out effect in thatregion. The runners or bracing bars 58' on one side of the arc chute areprovided with the bronze springs 280 connected as shown in Figure 5between the runners or bracing bars 58 by screws 281 and a latchassembly 6| secured thereto in any suitable manner as by the screws 283,283 (Figures 3 and 4) and having a projection 282 which engages acorresponding detent 284 in the laminated iron leg 55 (Figure 1). Thusthe arc chute is supported by the laminated legs 55 between runners 58on each side and is latched in position by the latch assembly 6|engaging detent 284 in laminated legs 55. To remove the arc chute it isonly necessary to press in the latch assembly 6| to disengage the detent284 from laminated iron legs 55 so that the arc chute may he slid out.As already stated, the arc chute is provided with a back are runner 290and a front are runner 29l converging below the arc chute and toward thecenter in the region of the contacts, the front are runner 29l havingextension 29! toward the contact and the rear arc runner 298 havingextension 290A toward the contacts and the further rearward extension293.

The portion l1lA (Figure 2) of the upper terminal to which lead 238 ofthe blow out coil is connected is also provided with the spring clip 300(Figures 1 and 2) to receive the rearward extension 283 of the rear archorn 290 of the arc chute 51. Thus no special connection need be madefor the arc chute; but when the arc chute is slid into position, therear extension 293 of the rear arc horn 290 moves into the spring clip30!! and the rear arc horn is thus connected to the end 238 of blow outcoil 54.

The section 2903 of the rear arc horn rests on plate Hi to obtainfurther contact to the rear are horn 290. Thus when the section of thestationary arcing contact jumps to section 290A 'ofxtherrear arc horn,theicurrent pathii's fromiterminalifll, :bolt;236 to lead-235 to coil54. to lead 238 tossection; IHA" of member IP'H andspringclip 300.. 1Then from spring clip 300 to sectionizsllb ofvrear arcr horn 2.8!). Thenthrough lithe are: chute to? the movablev rarcing contactandethenrtofthe:front arcrunner 29i as hereinafter morei specificallydescribed.

The cross plates-.260. asshown particularly in Figure 4 are each of aninsulating non-carbonizing m'aterialr preferabl'3 a glassbonded micaceramic material ,or 'aof a":- materiali-known as Transita These platesare longitudinal membersas' shown in Figures 4 and 5,, having a" curveat section 3830f a very large radius; upward'of this position they havea curve 304 ofsmaller rajdius";"and above that position have anextension 305 entering the notch 26s and closing off that side of theplate, r 1

llThei'side of each plate opposite the. curve-is flatl- When the arc isfirstdrawn it is driven upby the blowout mechanism "into the notch 3l0of v' shape'd cross section formed 'bythe curves 303-494 of thealternately arranged plates. As the arc is driven up further beyond theapex of the notch, it is caused to zigzag laterally in flowing past thecurves 304 of the alternately arranged plates. It thus passes throughthe relatively narrow notch on one side of one plate and then through asimilar relatively very narrow notch on the opposite side of thealternate plate and back and forth laterally through the arc chute.

If the arc is not extinguished when the arc has reached this point, themagnetic blow out blows the are up still further past extension 395where in addition to the lateral zigzagging and lengthening of the arc,the arc is zigzagged vertically. This combination of extreme lateralzigzagging with vertical zigzagging of the arc ensures extinguishment ofthe arc before the top of the arc chute is reached. The combination oflateral zigzagging with vertical zigzagging limits the upward travel ofthe arc.

Thus it will be seen that one of the essential elements of the arc chuteherein described is first the lateral zigzagging or lengthening of theare as it is blown up into alternating thin narrow slots on each side.Thereafter the portion of the arc between the cross-plates 260 is freeto move up to superimpose on the lateral zigzagging or lengthening ofthe arc, a vertical zigzagging or lengthening.

Also it will be seen that there is no connection whatever between thefront are horn 29l and the lower terminal or any other terminal when thecircuit breaker is closed or open.

It will be noted that extension 212 of the iron plate 21!] (Figures 3and 4) comes down on each side of the arc chute adjacent to the arcsbetween I'HB and 208 and also between I'HB and IE6. This increases theflux density at this point. The effect on the are between I'HB and 208which is horizontal is to drive it rapidly up the runners 290, '29l andinto the arc chute 51. The effect on the are between I'HB and IE6, whichis vertical, is to drive it back against the insulating and heatresisting block I58. This insulating block may be provided with slots,grooves, holes I63 or other cooling means to deionize the arc and efiectthe blow-out characteristics of the breaker. It will be apparent thatthe size, shape and spacing of the extensions 212 will also effect theblow-out characterist cs.

It will also be noted that the conductive bar l. this o i s'v u" t....,l I a? LH-rhas a, .u 'I'nQt i, dicated e nera1 xtJIiB therein; in;which.-the upper arcing horn- 2 01 registers,- thus provided for;simplified trans: ference..of.-the-,arc,gto the contact bar- UL. andhence tosection 29lla of the rear arc runner 290;;oi.the:arc chute ,5

, On -=funther; opening of the. contacts;-. the arc is.-b1own@up:into:the arczchute, the current path including contact .bar-,,3,0 .throug-hbolt 23 6 .an,d lead-$2,315 :through the blow-out coil, 54 ,and thenthroushrrspri g clip 390 a du n bana t0. 1' the; :arc: runner 1; 290.The are then passes throughcthe arc chute to; the front. are runner28:|i,;t.then 1to,thei-arcing-horn201 on the movable arcing contact :and,down through the moving contactstructure 8.0 ,to-t'he lower terminal-3|.

-:..It. will be ;seen"-thatrthe gap, between the.,arc ingz horn .-20|and section -29lB-of the. front are a; runnerissmall enou zhytorpermittransfer ofthe arct'toithefmnt ardrunner as; the contact movespast."ittrgdultinggopening; The q arc shou1d .b.e blown outabDut-Cthegtime the open position i reachedzor'very:"shortlrthereafter.- :sNormally the arc where the-shortcircuitpurrent is largewill be extinguished as the movable contact toward open position. In theevent of an opening of the circuit breaker with relatively low currentswhere there is relatively very low blow-out flux, then the arc maycontinue to be drawn until the movable contact reaches the openpositions, the are extending from section 29|B of arc runner 29l belowthis are runner to arcing horn 201 on the moving arcing contact 204 andthere the arc is cooled and blown out through the auxiliary arc chute320 (Figure 4) comprising the insulating side plates 269 carryingbetween them the spaced insulating plates 322 which are spaced bywashers 323 on bolts 324 which secure the plates 322 in position andalso secure the entire auxiliary arc chute 320 between the main sideplates 25! of the arc chute 51.

It will thus be seen that on opening of the circuit breaker underrelatively high overcurrent conditions, the arc is blown up and blowneven high and extinguished. In opening the circuit breaker on relativellow currents, a longer arcing path is relied upon, the double are beingdrawn where the upper section of the arc is extinguished by the coolingplates already described in the main arc chute, and the lower section ofthe are is extinguished by the auxiliary arc chute 320.

The insulating shield 230 above described in connection with Figure 2prevents a low current are from being blown down accidentall contactingthe terminal 3|. Oscillograph tests have shown the rates of arcextinguishment ranging from .58 cycle at 63,200 kva. (4200 volts) to 2.5cycles at 3728 kva. (5000 volts).

The arcing time may be even slower at lower voltage and curent values,but these values illustrate the efficiency of our novel device.

Since many variations and modifications of our invention should now beobvious to those skilled in the art, we prefer to be bound not by thespecific disclosure herein contained, but only by the appended claims.

We claim:

1. In a circuit breaker having contacts, an arc chute comprising aplurality of plates, a blowout coil, a blow-out iron circuit comprisinga core for said blow-out coil, and laminated iron plates connected tosaid core and extending at right angles to said core, said blow-out ironcircult being so arranged that the flux induced therein when currentflows in said coil is substantially evenly distributed over all of thesaid plate area for making maximum use of said are chute, and auxiliaryblow-out iron plates mechanically and magnetically attached to saidlaminated plates and extending at right angles to said plates towardsaid contacts on each side of said are chute for diverting a portion ofthe ablow-out field into the vicinity of the contacts, said blow-outstructure and are chute structure being mechanically separate andindependent of each other, said are chute being removable independent ofsaid blow-out structure, said blow-out structure acting as a support forsaid arc chute.

2. In a circuit breaker having an arc chute comprising a plurality ofplates, a blow-out coil, a blow-out iron circuit comprising a core forsaid blow-out coil, and laminated iron plates connected to said core andextending at right angles to said core, said blow-out iron circuit beingso arranged that the flux induced therein when current flows in saidcoil is substantially evenly distributed over all of the said plate areafor making maximum use of said arc chute, and

auxiliary blow-out iron plates mechanically and magnetically attached tosaid laminated plates and extending at right angles to said platestoward said contacts on each side of said are chute for diverting aportion of the blow-out field into the vicinity of the contacts, saidblow-out structure and are chute structure being mechanically separateand independent of each other.

JOSEPH D. WOOD. ARTHUR S. CASWELL.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,155,626 Steen Oct. 5, 1915 1,164,257 Carichofi Dec. 14, 19151,313,176 Evans Aug, 12, 1919 1,590,402 Aalborg June 29, 1926 1,603,820Wade Oct. 19, 1926 2,147,430 Ellis et a1 Feb. 14, 1939 2,240,654 Jochemet a1 May 6, 1941 2,255,886 Hudson Sept. 16, 1941 2,378,124 BolsterliJune 12, 1945

